Can I leave my T/C plugged in to A/C when not in use?

In my bus conversion I had triple banks with 7 batteries and having them in the storage, I would take only 2 engine batteries home for recharging.
Deep charge batteries hold good charge for full year.
Battery maintainer theoretically is the best option as it keeps battery from chemical destruction, but over the years I had couple of them malfunctioning and one boiled the battery dry, the other discharged it flat.
Now even when I have battery hooked up to float charger, I check the voltage about once a month.